1. Field of the Invention
This invention relates to riveting apparatus of the kind whereby a plurality of tubular blind rivets may be set in succession by drawing through the bore of each one of the rivets in turn an enlarged head of a riveting mandrel while the rivet is supported by an abutment.
2. Discussion of the Background
More particularly, the invention relates to riveting apparatus of the kind in which an elongated mandrel, having an enlarged head at one end and loaded with a plurality of the tubular rivets forming a column of rivets on the mandrel, is gripped by gripping means at or near the end remote from the head, and reciprocated relative to an abutment by relative reciprocation between the gripping means and the abutment, and in which a pneumatically operated rivet-feeding means applies a thrust to the column of rivets to urge the column forwardly along the mandrel towards the head of the mandrel so that the rivet nearest the head of the mandrel becomes disposed forwardly of the abutment, and can then be set by moving the mandrel rearwardly relative to the abutment so as to draw the head of the mandrel through the bore of the rivet while the rivet is supported by the abutment. Such apparatus is hereinafter referred to as the "riveting apparatus of the kind defined".
The abutment is usually provided by a nosepiece comprising jaws between which the mandrel extends, and which are separable to allow rivets which are fed forwardly along the mandrel to pass between them, the jaws being spring urged to close together behind a fed rivet which has passed forwardly of the jaws, and to resist rearward movement of the fed rivet.
Relative reciprocation between the abutment and the mandrel gripping means can be produced by either pneumatically or hydraulically powered means.
There is a danger with such tools that, if pneumatic power is applied to the rivet-feeding means at a time when the mandrel is not gripped securely by the gripping means, then the mandrel and its load of rivets can be expelled, forcefully, from the tool by the operation of the rivet feeding means.
In some such tools, the gripping means is in the form of a chuck having jaws which have to be closed on the mandrel by manual rotation of a jaw-adjusting device. Safe operation of such tools relies on the operator clamping the loaded mandrel in the tool in this manner before causing the rivet-feeding means to operate.
Such a tool is described in GB 1183049, corresponding to U.S. Pat. No. 3,557,597, which also describes a modification of the tool in which the gripping means is pneumatically operated. Thus, in the modification, both the rivet-feeding means and the mandrel gripping means are pneumatically operated by a common supply of air or other suitable gas under the primary control of a single on/off valve provided in an air-supply pipeline at a position more or less remote from the tool.
In order to ensure that the rivet feeding means could not operate if the mandrel were not gripped by the gripping means, it was necessary to provide the tool with means whereby the operation of the rivet feeding means would be disabled if the mandrel was not gripped by the gripping means. In the embodiment described in U.S. Pat. No. 3,557,597, the disabling means takes the form of a valve (57a, 75, 76) which is opened automatically so as to vent to atmosphere the air supply for the rivet-feeding means, by an extended movement of the gripping means, when the gripping means moves to grip a mandrel but fails to engage a mandrel.